A novel force transducer using thin steel foils and laser beam reflection achieved a resolution of approximately 18 nN rms, allowing measurement of 0.2% of the maximum isometric force of a single cardiac myocyte.
The described force transducer provides sufficient temporal resolution and sensitivity to accurately measure mechanical properties and rapid force responses in single cardiac myocytes.
We have described a transducer design capable of recording forces generated by single cardiac myocytes with sufficient temporal resolution to detect force responses to rapid length changes. Our force sensors were made from thin steel foils that act as cantilevers whose bending is monitored by reflection off a laser beam. Deflection of the laser beam is measured by a differential photodiode detector. A small, 50-micron-thick tungsten needle attached to the free end of the steel foil allowed us to glue single cardiac cells to the force transducer. The transducers have compliances of approximately 0.02 m/N and resonance frequencies between 2 and 3 kHz. The resolution is approximately 18 nN rms at a detector bandwidth of 16 kHz, so we were able to resolve 0.2% of the maximum isometric force ( approximately 12 microN) developed by a single cardiac myocyte. We have demonstrated that the transducer is well suited to analysis of mechanical properties of single ventricular myocytes, for example, the recording of isometric forces and rate constants of force redevelopment after rapid release-restretch maneuvers.
Tasche et al. (1999) studied Single cardiac myocytes. Force transducer was evaluated on Transducer performance (compliance, resonance frequency, resolution). A novel force transducer using thin steel foils and laser beam reflection achieved a resolution of approximately 18 nN rms, allowing measurement of 0.2% of the maximum isometric force of a single cardiac myocyte.